A variety of needle-free medical connectors are currently commercially available. Such connectors are generally used in handling and administering parenteral fluids, especially fluids associated with extension sets and patient catheters. These connectors are more specifically designed to interface, on a fluid dispensing and acquiring end, with a first, usually female, luer fitting, thereby to interface with fittings such as those commonly found on conventional syringes. On the other end, often, interface is through another luer fitting to provide a needleless communicating link to a catheter or an extension set affixed to a catheter.
An example of a needle-free connector is disclosed in U.S. Pat. No. 7,244,249 B2, titled NEEDLE-FREE MEDICAL CONNECTOR WITH EXPANDABLE VALVE MECHANISM AND METHOD OF FLUID FLOW CONTROL, issued Jul. 17, 2007 to Karl R. Leinsing, et al., and (Leinsing). Similar technology is also disclosed in U.S. Pat. Nos. 7,306,199, 7,184,825, 7,104,520, 6,706,022, 6,706,022, D468,016, 5,676,346 and 5,549,577. Leinsing discloses a needle-free connector having a two part housing and an associated piston element which is also made of two parts and contained within the housing. One of the piston element's parts is disposed within the other element part. The outer part has a compressible section which is compacted by insertion of a cannula into the housing and against the piston element to actuate a self-opening valve. The valve self-opens when the piston element is displaced from a state at a first position to a second position. Energy stored in the compressed section returns the piston element to the first position and valve closed resting state upon removal of the cannula which displaced the piston element part for such actuation.
Another example of a needle-free connector is disclosed in U.S. Pat. No. 5,901,942, titled MEDICAL VALVE, issued May 11, 1999 to George A. Lopez (Lopez). Lopez discloses a needleless valve device which utilizes a hollow spike having a closed tip to pierce a seal as the seal is forced across the tip by an ANSI tip of a medical implement. By so forcing the tip against the seal, the seal is displaced, permitting side holes within the tip to be open to fluid flow.
An example of a slit-valve free needleless connector is disclosed in U.S. Pat. No. 5,782,816, titled BIDIRECTIONAL VALVE AND METHOD OF USING SAME, issued Jul. 21, 1998 to Gary S. Werschmidt, et al. (Werschmidt). Werschmidt discloses a plug which is displaced within a housing by an inserted luer fitting to open access to a pathway there through. Of note is axial compression of the plug to a canted position to permit the access. Concern for such compressible plugs is possible reflux which may result when the plug is permitted to decompress when the luer fitting is removed and a lack of a closed seal about an inserted cannula tip.
Analysis of these approaches to needle-free design and general requirements of such connectors yields a number of important connector properties including needs for:
1. Inherently low manufacturing cost, making disposal after use efficacious.
2. Low dead space.
3. Ability to be sterilized before use to assure an initially uncontaminated product.
4. An accessible entry point for a cannula (e.g. a male luer fitting)
5. Facility for swabbing or otherwise cleaning the entry point to protect against contamination of fluids transferred through the connector.
6. Leak-free connection between a communicating cannula (e.g. a luer fitting of a syringe) and an associated valve component disposed as an integral part of each needle-free connector
7. A normally closed valve which is opened upon insertion of the cannula (e.g. a male syringe luer fitting) to permit bidirectional fluid flow through the connector and which is self-closing upon removal of the cannula or fitting.
8. Providing a positive pressure in residual fluid in the connector upon valve closure to obstruct retrograde (reflux) flow from a downstream positive pressure source upon valve closure
9. Internal pathways through the connector which are readily flushed to clear residual liquid from the connector as a result of a flush cycle, thereby reducing dangers associated, for example, with hazardous drug retention and incompatible drug mixing.
10. Capacity for retaining the cannula in place throughout a fluid transfer procedure.
11. Ability to securely interface with a female luer associated with communicating with a catheter or extension set (in at least one design).